1. Field of the Invention
The present invention relates to a foreign substance removing device and a die bonder equipped with the same.
2. Description of the Related Art
The die bonder is an apparatus which bonds a die (silicon wafer chip integrating electric circuits) to a lead frame, substrate or the like (hereinafter, referred to as “substrate”) using solder, gold plate or resin as a bonding material. An engineering plastic is used as a die bond material (paste, film) for bonding the die and the substrate together. After positioning, the die is bonded to the lead frame or the like. A method of implementing bonding by using a resin as the bonding material is now predominant.
In semiconductor die bonding, solder or resin paste for die bonding (Ag epoxy and Ag polyimide) is used as an adhesive for fixing a semiconductor chip (IC, LSI) to the lead frame, ceramic case, substrate or the like.
Dusts on a substrate surface lower the bonding force of an adhesive. It is therefore quite important in die mounting to remove the dusts (hereinafter, referred to as “foreign substances”) from the substrate before bonding the die onto the substrate. In addition, foreign particles of sizes in the range of 5 to 10 μm also cause voids in the adhesive.
Accordingly, a common practice in a die bonding operation is to perform cleaning with air flow. Such cleaning techniques known in the art are set forth in the following patent documents.
JP-A No. 2002-50655, for example, discloses an arrangement wherein plural types of cleaning devices are arranged along a transport path for horizontally transporting the substrate so that the substrate being transported is subjected to cleaning before chips are mounted thereon.
JP-A No. 2002-186923 discloses an arrangement wherein the foreign substances adhered to the substrate surface is vacuumed off by a dust collector.
JP-A No. 2000-5715 discloses an apparatus wherein a dust removing device integrating an air outlet chamber and an air inlet chamber is disposed in a moving direction of a work piece.
JP-A No. 2007-115979 discloses an arrangement wherein the foreign substances adhered to a surface of a wafer ring carrying a chip array thereon are removed by blasting an ionized gas followed by sucking.
As described in the above patent documents, the removal of the foreign substances on the substrate surface is generally accomplished by a method wherein the foreign substances are blown off by applying an air flow and the blown foreign substances are collected by air suction. Unfortunately, however, all these patent documents adopt a stationary system of foreign substance removal, which comes short of ensuring an efficient foreign-substance removal across the full width of substrate and preventing the readhesion of once removed foreign substances.